In ceramic cisterns, cistern elevations and lid elevations are likely to change from one cistern to another. Generally, variations in elevation are of a few millimeters but may be in excess of tens of millimeters.
Usually, pre-adjustment of the elevation of the flushing mechanism is carried out by using the bracket which connects the upper part of the mechanism bearing the control button, and the lower part bearing the valve. This bracket includes two vertical arms provided with teeth regularly distributed on the arm's elevation generally with a 15 mm step. It happens that a pre-adjustment carried out by means of the bracket's teeth brings the control button exactly to the elevation of the top of the lid of the ceramic cistern.
However, usually the control button's position has to be adjusted. This adjustment is carried out by removing the control button and by cutting with an appropriate tool the vertical rod imparting the control pressure to the swivelling arm which provides, via a pull handle, for opening of the valve. The control button is then put back into place.
The technical problem posed by the adjustment of the control button's position is critical in the case of a flushing mechanism capable of providing two flushes of different volumes by means of two buttons placed side by side. The two vertical rods must then be cut to the same elevation, if either of them is cut too short, it must be replaced. That is why in the proposed assemblies for fitting to cisterns, flushing mechanisms are accompanied by several, generally four or five, rods.